1. Field of the Invention
The field of this invention includes methods and machines for on-line recycling of both oriented and unoriented film produced on a film extrusion line.
2. Prior Art
Systems for on-line recycling of edge trim produced by a film extrusion line are known and work reasonably well. However, such systems have been generally unsuccessful when applied to oriented tapes produced from oriented or unoriented slit films. The reason apparently being that static charges from the oriented film results in "balling" or "bridging" (terms common to the art) that cause blockages in these systems. Such blockages cause the output of an extruder to surge (too much flow) or to starve (too little flow).
U.S. Pat. Nos. 4,014,461 (1977) and 3,797,702 (1974) both to J. D. Robertson disclose an example of a recycle or reclaim system which works well on edge trim recycled from a film extrusion line, but eventually has problems during production due to bridging when low density reclaim contains oriented film in addition to edge trim.
"Low density reclaim" means chopped film which has an apparent density of less than about 9 pounds/cubic feet (lb/cf). The apparent density is the weight of chopped film which without either induced settling thereof such by shaking of the container or pressure applied thereto just fills a 1 cubic foot container when added thereto after a loose freefall of at least 2 inches but not in excess of about 12 inches.